Answer:
phosphorus - least similar to barium
beryllium - most similar to barium
Step-by-step explanation:
The formula of the chloride formed between barium and chlorine is BaCl2.
Barium is a metallic element and has the valency of +2. Beryllium is also a group two metal with a valency of +2. Hence the compound formed between beryllium and chlorine is BeCl2
Phosphorus is a nonmetal and forms a completely different chloride from BaCl2. The chloride of phosphorus is PCl5 and PCl3. These are least similar to BaCl2